An aircraft ejector rack is used for forcibly ejecting stores carried by an aircraft during flight so that the stores are safely ejected away from the aircraft. An ejector rack typically includes a pair of piston-and-cylinder type thrusters which have reciprocating rams operated by pressurized fluid, such as gas generated by a pyrotechnic device or stored in an accumulator. The thrusters are arranged generally parallel and spaced apart along the length of a store. Simultaneous operation of the thrusters causes the store to be rapidly accelerated and ejected.
A requirement often imposed on ejector racks is the capability of selectively varying the flow rate of pressurized fluid to the thrusters, both to control the energy level imposed on the store as well as to control pitch rate of the store as it is ejected. One method of selectively varying the flow rate to the thrusters has been to incorporate a removable and replaceable orifice device between the source of pressurized fluid and the thrusters. The replaceable orifice device typically is a threaded plug or insertable rod having a metering orifice which is placed in the flow path. Disadvantages of such ejector systems include the necessity to at least partially disassemble the ejector in order to change the orifice device, and the need for maintaining an inventory of various sizes of orifices.
An alternative to ejectors with replaceable orifices is described in U.S. Pat. No. 4,043,525, assigned to the assignee of the present application and incorporated entirely herein by reference. The ejector disclosed in the '525 patent has a variable orificing device which permits variable apportioning of flow between the thrusters without disassembling the ejector. The device includes a pressure chamber having an inlet through which pressurized fluid enters and two outlets through which the fluid passes to the forward and aft thrusters, respectively. A metering cylinder or rod is disposed in the pressure chamber and can be rotated within the chamber or, alternatively, translated within the chamber, to simultaneously vary the flow through the two outlets. The flow-apportioning device described in the '525 patent is highly effective. However, incorporating the flow-apportioning device into an ejector rack necessitates the addition of several precision-machined mechanical components. Accordingly, the device increases the size, weight, and manufacturing and assembly costs of an ejector rack.